The present invention relates to coaxial cable surge protectors, and more particularly to a surge protector/connector assembly that provides an integral fuse link.
Telecommunications systems, such as cable television set-top boxes, Internet cable modems, and satellite TV receivers, are vulnerable to lightning surges and other fault conditions. Various types of surge protectors have been designed and manufactured for protecting coaxial transmission lines, and associated equipment, from damage due to transient voltage and current surges.
Coaxial based networks provide voice, video and data services to an increasing number of users. Broadband coaxial systems require surge protectors to handle current and voltage surges to protect personal and often expensive electronic equipment while not interfering with signal transmission.
Prior art surge protectors generally included separate components to protect against voltage and current surges. One type of prior art surge protector is a gas discharge tube connected between the inner conductor and the outer conductor of a coaxial cable. Such a surge protector protects against transient voltage surges.
Other surge protectors include a fail-short mechanism that protects against sustained voltage surges. Such mechanisms short the inner and outer conductors of a coaxial cable together when a voltage greater than a specified threshold persists on the coaxial cable (e.g., for 15 minutes), thus allowing the fail-short mechanism to conduct a fail-short current to ground.
Another prior art surge protector is a fuse element placed in series with a coaxial cable. Such a fuse protects against over-current conditions caused by lightning and/or electrical transients. When a current surge occurs, the fuse melts, creating an open circuit that protects the cable and the attached equipment from damage. Prior art fuse elements are external to coaxial cable connectors and/or protectors, generally comprised of a small gauge (thin) section of coaxial cable connected between a voltage surge protector and a coaxial cable transmission line.
Consequently, there is a need for an integral surge protector/coaxial cable connector that provides current surge protection and which is microwave transparent, simple to install, small in size, and inexpensive to manufacture. The claimed surge protector is designed to eliminate the need for an external over-current protector by providing a coaxial connector with an integral fuse link. The claimed design is less expensive to produce than non-integral designs. In addition, the claimed protector may further include components that prevent damage to a protected coaxial cable, and its associated electronic equipment, due to over-voltage conditions.
In one embodiment, a coaxial transmission line surge protector assembly is provided which includes a connector housing having an outer conductor surface for electrically coupling with the outer conductor of a coaxial transmission line. A housing inner conductor, for electrically coupling with the inner conductor of a coaxial transmission line, which includes a fuse link that becomes an open circuit when the current through the fuse link is greater than a current threshold.
In another embodiment, the protector assembly further includes a gas tube having first and second electrodes for electrically coupling with the outer and inner conductors of a coaxial transmission line.
In a further embodiment, the protector assembly includes a fail-short clip having a first portion that is electrically coupled to the first electrode of the gas tube and a second portion that is electrically insulated from the second electrode of the gas tube by a dielectric.
Additional novel features and advantages of the present invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.